1. Field of the Invention
The present invention relates to an integrated circuit having at least one terminal for coupling and/or decoupling of electric signals, particularly of digital signals, and having integrated reference potential means, assigned to the terminal, for providing an electric reference potential to the terminal.
2. Description of the Background Art
Conventional integrated circuits are realized as a semiconductor component and have a plurality of internal and external terminals. The internal terminals are formed as nodal points of electric conductors between individual circuit components, realized in the circuit, such as resistors, capacitors, or transistors. The external terminals are realized as electromechanical interfaces, which typically enable an electrical connection of the integrated circuit with a printed circuit or other electrical components via bond wire connections or solder ball connections. To assure the proper functioning of the integrated circuit, it is desirable that each terminal at each point in time has a defined electric potential. As a result, interference by electric signals, which, for example, are applied at neighboring terminals and can be transmitted via inductive or capacitive couplings, can be avoided.
The prior-art integrated circuit for this purpose has reference potential means at terminals that are not assigned any permanent and clear electric potential or a corresponding useful signal. The reference potential means apply a defined electric potential at the terminal in absence of the useful signal. Known reference potential means are realized as pull-up circuits or as pull-down circuits. In this case, a terminal is connected to a higher or lower voltage potential via a high-impedance resistor, so that in the absence of a useful signal the terminal has the corresponding voltage potential. As soon as a useful signal is applied to the terminal, the electric potential at the terminal is defined by the useful signal due to the high-impedance coupling of the pull-up circuit or the pull-down circuit. Because of the high-impedance resistor, reference potential means made in this manner require a certain area on the integrated circuit and are not suitable for all types of terminals.